1. Field of the Invention
The present invention relates generally to an ink jet printing method, an ink jet head used for practicing the latter, an ink jet cartridge and an ink jet printing apparatus which can obtain a high quality of image on a printing medium. More particularly, the present invention is applied to ink jet printing which is effective for ejecting to the printing medium printability improvement liquid for making a coloring substance in the printing ink and the printability improvement liquid insoluble or aggregating them. Accordingly, the present invention can be applied to all apparatuses and equipment each using a printing medium such as a sheet of paper, cloth, leather, unwoven cloth, OHP paper, metallic sheet. A concrete apparatus and equipment to which the present invention can be applied is exemplified by copying machine, facsimile, printer, word processor and output terminal of computer.
Incidentally, the meaning of a term "print" includes application of ink (printing, image forming, recording and dyeing) to all ink carriers adapted to receive ink application, such as cloth, thread, paper, sheet material or the like.
2. Description of the Related Art
Conventionally, since the ink jet printing method generates low noise, it is practiced at a low running cost and it is easy to design and construct an apparatus and operate the apparatus with colors, the ink jet printing apparatus is used and commercially sold as a printer serving as an output terminal for, e.g., facsimile, electronic typewriter, word processor, work station or the like or as handy or portable printer to be equipped on personal computer, host computer, optical disc device, video apparatus or the like. In this case, the ink jet printing apparatus is constructed in correspondence to a function, a pattern of use or the like of these devices and apparatuses.
Generally, the ink jet printing apparatus includes a carriage having printing means (print head) and an ink tank carried thereon, conveying means for conveying a printing medium and controlling means for controlling them. In practical use, a printing head for ejecting ink droplets from a plurality of ejecting ports is serially scanned in the direction (main scanning direction) perpendicular to the conveying direction (auxiliary direction) of the printing medium, and during a non-printing operation, the printing medium is intermittently conveyed by a distance equal to a recording width. In addition, by using the printing head having a number of nozzles each adapted to eject ink therefrom arranged on a straight line extending in the auxiliary direction, recording is achieved with a width corresponding to the number of nozzles by allowing the printing head to once scan on the printing head. With this construction, it is possible to perform a recording operation at a higher speed.
In the case of a color ink jet printing apparatus, a colored image is formed by superimposing ink droplets ejected from plural colors of printing heads on one another. Generally, in the case that color printing is performed, three kinds of printing heads corresponding to three primary colors composed of yellow (Y), magenta (M) and cyan (C) or four kinds of printing heads corresponding to three primary colors plus black (Bk) and an ink cartridge are required. Recently, a color ink jet printing apparatus having three or four kinds of printing heads mounted thereon and having a possibility that an image is formed with full color has been put in practical use.
However, in the case that an image is formed on a printing medium that is called a plain paper, with the use of the printing apparatus to which the ink jet printing method is applied, the resultant image has insufficient water resistibility, and in the case that a color image is obtained, a color image having excellent image rigidity and acceptable image quality because requirement for an image having a high density without any occurrence of feathering and requirement for an image having no occurrence of oozing between adjacent colors can not simultaneously be met.
In recent years, as a method of improving water resistibility of an image, ink allowing a coloring material contained therein to have water resistibility has been put in practical use. However, since the foregoing ink has still insufficient water resistibility, and is ink which is hardly soluble in water in principle after the printed image is dried, it is presumed that nozzles in the printing head are readily clogged with the coloring material. To prevent this malfunction, however, the conventional type of simple printing head structure and ink jet printing apparatus structure is not sufficient, and it is presumed that apparatus structure corresponding to printability improvement liquid becomes complicated.
Many technologies for improving rigidity of a printed article have been hitherto disclosed. A technology of transforming dyestuff into lake which is fixedly secured to a dyed article by aftertreating the latter in order to improve rigidity of the dyed article in a wetted state is disclosed in Japanese Patent Application Laid-Open No. 24486/1978.
A printing method of printing by employing an ink jet printing process using two or more components of which film forming ability is increased at the room temperature or in a heated state when they come in contact with each other is disclosed in Japanese Patent Application Laid-Open No. 43733/1979. With this method, there is obtained a printed article having a film formed thereon while it is firmly secured to a printing medium by allowing the components to come in contact with each other on the printing medium.
A method of applying a water resisting agent for forming dyestuff and lake after an aqueous dyestuff ink is printed by employing an ink jet printing process is disclosed in Japanese Patent Application Laid-Open No. 150396/1980.
An ink jet printing method wherein an image position to be printed is preliminarily identified and print ink and treatment ink are printed in a superimposed state is disclosed in Japanese Patent Application Laid-Open No. 128862/1983. In this document, a method wherein an image is scribed with print ink prior to the print ink, the treatment ink is superimposed on the scribed print ink, and the print ink is superimposed on the scribed treatment ink, and moreover, the treatment ink is scribed in the superimposed state is disclosed.
As described above, on the assumption of the conventional head structure, with the method of ahead feeding wherein the head structure having only a printability improvement liquid head added thereto is combined with the conventional printing method, i.e., the printability improvement liquid is shot prior to ink and/or the method of behind feeding, i.e., the printability improvement liquid is superimposed on the ahead shot ink, it can not expected that a quantity of use of the printability improvement liquid is reduced and an effect derived from the printability improvement liquid and a printing speed are improved. Especially, the inventor has found that it is not only impossible to estimate an effect of ahead feeding and/or behind feeding treatment, e.g., permeation control, bleed reduction, reduction of fluctuation/stripe, head structure, printing method, time until the printability improvement liquid comes in contact with colored ink, permeating state of each ink on the printing medium, and state directly after ink printing and sufficiently exhibit the effect but also it is unavoidable that the printing speed is reduced (inclusive of low speed control of driving frequency, temporary stop of printing or the like) to maintain the effect to a certain extent, causing reduction of throughput of printing and increase of the running cost to arise.